Aqueous adhesive compositions containing stabilized phenolic resins

Abstract

An aqueous primer composition containing a polyvinyl alcohol-stabilized aqueous phenolic resin dispersion, a latex of a halogenated polyolefin, and a metal oxide. The phenolic resin dispersion is prepared by mixing (a) a pre-formed, solid substantially water-insoluble, phenolic resin; (b) water; (c) an organic coupling solvent; and (d) polyvinyl alcohol, at a temperature and for a period of time sufficient to form a dispersion of said phenolic resin in water. The aqueous primer composition substantially reduces the utilization of organic solvents, is resistant to pre-bake conditions, and provides for a robust adhesive bond which is flexible and resistant to adverse environments.

What is claimed is: 
     
       1. An aqueous primer composition comprising a polyvinyl alcohol-stabilized aqueous phenolic resin dispersion, a latex of chlorosulfonated polyethylene, and a metal oxide. 
     
     
       2. The primer composition according to claim 1 wherein the phenolic resin dispersion is prepared by a process comprising mixing: (a) a pre-formed, solid, substantially water-insoluble, phenolic resin;   (b) water;   (c) an organic coupling solvent; and   (d) polyvinyl alcohol, at a temperature and for a period of time sufficient to form a dispersion of said phenolic resin in water.   
     
     
       3. The primer composition according to claim 2 wherein the phenolic resin is a solid resole or novolak phenolic resin. 
     
     
       4. The primer composition according to claim 3 wherein the resole phenolic resin is a base catalyzed resin having a formaldehyde factor of about 90 to about 180 and the novolak phenolic resin is an acid catalyzed resin having a formaldehyde factor of about 50 to about 75. 
     
     
       5. The primer composition according to claim 1 wherein the phenolic resin is prepared from a substituted or unsubstituted phenol. 
     
     
       6. The primer composition according to claim 5 wherein the substituted phenol is selected from the group consisting of cresol; bisphenol-A; and para-substituted phenols. 
     
     
       7. The primer composition according to claim 1 wherein the phenolic resin is a resole phenolic resin produced by reacting formaldehyde with bisphenol-A in a mole ratio from about 2 to about 3.75 moles of formaldehyde per mole of bisphenol-A in the presence of a catalytic amount of an alkali metal or barium oxide or hydroxide condensation catalyst, the reaction being carried out at elevated temperatures and the condensation reacting product being neutralized to a pH of from about 3 to about 8. 
     
     
       8. The primer composition according to claim 2 wherein the coupling solvent is selected from the group consisting of alcohols, ethers, esters, and ketones. 
     
     
       9. The primer composition according to claim 2 wherein the coupling solvent is selected from the group consisting of ethanol, n-propanol, isopropyl alcohol, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monopropyl ether, and methoxy acetone. 
     
     
       10. The primer composition according to claim 1 wherein the chlorosulfonated polyethylene has a molecular weight in the range of about 50,000 to 150,000; a chloride content in the range of about 20 to 50; and a sulfur content in the range of about 0.5 to 2. 
     
     
       11. The primer composition according to claim 10 wherein the molecular weight of the chlorosulfonated polyethylene is in the range of about 60,000 to 120,000; the chlorine content is in the range of about 25 to 45; and the sulfur content is in the range of about 1.0 to 1.5 percent. 
     
     
       12. The primer composition according to claim 1 wherein the metal oxide is an oxide of zinc, cadmium, magnesium, lead, or zirconium; zirconium salts; or combinations thereof. 
     
     
       13. The primer composition according to claim 12 wherein the metal oxide is zinc oxide. 
     
     
       14. A primer composition comprising from about 20 to 80 percent by weight of a polyvinyl alcohol-stabilized aqueous phenolic resin dispersion, from about 10 to 40 percent by weight of a latex of chlorosulfonated polyethylene, and from about 10 to 80 percent by weight a metal oxide. 
     
     
       15. The primer composition according to claim 14 wherein the phenolic resin dispersion is present in an amount from about 40 to 60 percent by weight, the latex of chlorosulfonated polyethylene is present in an amount from about 15 to 25 percent by weight, and the metal oxide is present in an amount from about 20 to 40 percent by weight.